Method of and an apparatus for readjusting the anodes in the cells of electrolysis plants

ABSTRACT

APPARATUS FOR COMMON ADJUSTMENT OF THE POSITION OF A GROUP OF ANODES IN AN ELECTROCHEMICAL CELL, INCLUDING A CELL CASING HAVING AN OPENING WITH A COVER CLOSING THE OPENING, AN INFLATABLE LIFTING TUBE SEALING THE EDGES BETWEEN THE CASING AND COVER AND CARRYING THE COVER, A GROUP OF ANODES MOUNTED IN THE COVER, A PRESSURE FLUID SOURCE FOR INFLATING THE TUBE, AND CONTROL MEANS OPERATIVELY CONNECTING THE TUBE AND PRESSURE FLUID SOURCE FOR ADJUSTING THE QUANITY OF PRESSURE FLUID IN THE TUBE AND CORRESPONDINGLY THE DISTANCE BETWEEN THE COVER AND CASING TO VARY THE POSITION OF THE ANODES WITH RESPECT TO THE CASING: AND METHOD OF ADJUSTING THE POSITION OF A GROUP OF ANODES WITH RESPECT TO THE CATHODE OF AN ELECTROCHEMICAL CELL INCLUDING A CASING CONTAINING SUCH CATHODE AND HAVING AN OPENING CLOSED BY A COVER IN WHICH SUCH   ANODES ARE MOUNTED, IN WHICH PRESSURE FLUID IS MAINTAINED IN A CONFINED TUBULAR ZONE, OF TRANSVERSE HEIGHT WHICH VARIES IN DEPENDENCE UPON THE QUANITY OF PRESSURE FLUID IN SAID ZONE IS MAINTAINED IN SEALING CONTACT WITH SAID CASING AND COVER AND CARRIES THE WEIGHT OF THE COVER, THE CELL VOLTAGE IS SENSED BETWEEN THE ANODES AND CATHODE, AND THE QUANITY OF PRESSURE FLUID IS ADJUSTED IN SAID ZONE IN DEPENDENCE UPON CHANGES IN THE SENSED CELL VOLTAGE TO ADJUST CORRESPONDINGLY THE TRANSVERSE HEIGHT OF SAID ZONE AND IN TURN THE POSITION OF SAID COVER AND GROUP OF ANODES WITH RESPECT TO THE CATHODE.

METHOD OF AND AN APPARATUS FOR READJUSTING THE ANODES IN THE CELLS OF ELECTROLYSIS PLANTS Filed Feb. 26, 1968 INVENTOR.

JOHANN SENSEN United States Patent M Int. C1. C23]: 70; 1301!: 3/00 US. Cl. 204-225 9 Claims ABSTRACT OF THE DISCLOSURE Apparatus for common adjustment of the position of a group of anodes in an electrochemical cell, including a cell casing having an opening with a cover closing the opening, an inflatable lifting tube sealing the edges between the casing and cover and carrying the cover, a group of anodes mounted in the cover, a pressure fluid source for inflating the tube, and control means operatively connecting the tube and pressure fluid source for adjusting the quantity of pressure fluid in the tube and correspondingly the distance between the cover and casing to vary the position of the anodes with respect to the casing; and method of adjusting the position of a group of anodes with respect to the cathode of an electrochemical cell including a casing containing such cathode and having an opening closed by a cover in which such anodes are mounted, in which pressure fluid is maintained in a confined tubular zone, of transverse height which varies in dependence upon the quantity of pressure fluid in said zone, while said zone is maintained in sealing contact with said casing and cover and carries the weight of the cover, the cell voltage is sensed between the anodes and cathode, and the quantity of pressure fluid is adjusted in said zone in dependence upon changes in the sensed cell voltage to adjust correspondingly the transverse height of said zone and in turn the position of said cover and group of anodes with respect to the cathode.

This invention relates to a method of and an apparatus for adjusting the anodes in the cells of electrolysis plants, particularly those used for the electrolysis of alkali metal chlorides, in which all the anodes of one cell are arranged on a common adjusting system.

So-called group-adjustment systems in which the anodes of one cell can be simultaneously adjusted by an upward and downward movement are already known. In arrangements of this kind, the anodes are mounted on a common stable supporting frame which is moved. In one embodiment, the anodes extend through stufling boxes arranged in the lid or cover of the cell. The disadvantage of this kind of arrangement is that it incorporates a large number of sealing surfaces which are subject to considerable wear and, due to the hazards emanating from any gases escaping, have to be constantly inspected and repaired where necessary. In another embodiment therefore, the rigid cover fitted with stuffing boxes is replaced by an elastic gland or diaphragm through which the anodes project upwards in a gas-tight manner. Unfortunately, this diaphragm is burnt through very easily in the event of short circuits so that once again gases can escape. In both embodiments, an expensive supporting frame has to be used as the means for adjusting the anodes.

It is also known that a cell cover provided with rollers by which it is mounted on rails can be sealed by means of a tube arranged between the cover and the cell casing. In this case, the tube merely acts as a sealing element so 3,556,973 Patented Jan. 19, 1971 that the additional equipment referred to above has to be used to support the cover.

It has now been found that these disadvantages can be obviated by mounting the anodes in the lid of the cell and by providing between the edge of the lid and the edge of the cell casing an elastic, fillable tube in the form of a lifting element which supports the lid of the cell and is connected to a pressure system in turn connected to a control unit. This arrangement provides a simple, lightweight supporting frame for the anodes, the fillable tube simultaneously acting both as a lifting element for the set of anodes and as a sealing element between the lid of the cell and its casing. Another particular advantage of this simple arrangement is that, when an anode becomes damaged, the entire lid of the cell, together with the anodes, can be replaced as a unit in a very short time, the only work involved being to unclip the old unit from the conductor rail and to replace it with the new unit.

The tube can be connected to a pneumatic or hydraulic pressure system. It is preferably divided into separate compartments which are appropriately connected to the pressure system. As a result, the apparatus is more reliable in operation should the tube develop a leak. For example, the entire electrolysis plant may be provided with a single pump or compressor in whose distributor pipe system an inlet valve and an outlet valve are provided for each cell. In one particular embodiment of the invention, the inlet and outlet valves for each cell are connected to a separate control unit which, at the inlet end, is connected with the cell through a voltmeter for measuring the cell voltage. Thus, in accordance with the invention, the anode can be adjusted by varying the level to which the tube is filled in dependence upon the cell voltage between the cathode and the conductor rails of the anode, the measured voltage being fed to a transmitter which converts it into a regulating pulse which is processed into a control pulse acting on the inlet and outlet valves incorporated in the pressure system. This is preferably done by establishing a desired value for the cell voltage whose effective value is compared with the desired value and constantly adapted thereto by readjusting the anodes. The throughflow cross-section of the inlet valve is preferably greater than that of the outlet valve. In this way, the tube can be filled quickly and emptied slowly, i.e., the lid of the cell can be raised quickly and lowered slowly. The advantage of this lies in the possibility of quickly varying the gap between the anode and cathode in the event of short circuits. By virtue of the gradual lowering, it is possible to set out the electrode gap very accurately.

It is of advantage to manufacture the tube arranged between the lid and casing of the cell from a material which is resistant to moist chlorine gas, or to coat it with such a material. Polytetrafluoroethylene (Teflon) is suitable for this purpose.

Another advantage of the apparatus according to the invention is that the cell is only sealed by the weight of its lid. In the event of sudden increases in pressure in the cell, the lid acts as a safety valve which opens early so that the gas can escape without any danger of explosion.

One embodiment of the apparatus according to the invention is illustrated by way of example in the accompanying drawings. The anodes 2 are connected to the conductor rail 1 through flexible connecting bands or straps 3. The anodes 2 are mounted in the lid 4 of the cell whose edge 5 rests on the fillable tube 6 which in turn rests on the edge 7 of the cell casing 8. The references 9 and 10 denote guides for the lid 4 and the tube 6. The anodes 2 can be set at a certain distance from the mercury cathode v11 flowing along the bottom 12 of the cell. A pipeline 13 leads from the tube 6 to the pipe 14 in which the inlet valve 15 and the outlet valve 16 are arranged.

The pressure system is fed through the pump 17 which takes its supply from the tank 18 and into which the liquid under pressure is also returned.

In cases where a pneumatic pressure system is used, the pump 17 is replaced by a compressor taking in air from the atmosphere. The air is also discharged back into the atmosphere.

The cell voltage is tapped between the cathode 11 and the conductor rail 1 and measured by a voltmeter '19. If it does not agree with the desired voltage, the measured voltage is converted in a transmitter 20 into a regulating pulse which is processed in a pulse converter 21 into a control pulse acting on the valves 15 and 16.

I claim:

1. Apparatus for common adjustment of the position of a group of anodes in an electrochemical cell, which comprises a cell casing having means defining an opening therein, a cover normally closing said opening, a group of anodes mounted on said cover and extending into said casing, an elastic fillable lifting tube interposed operatively between said casing and cover and arranged to carry said cover, means defining a source of pressure fluid in flow communication with said tube, and control means operatively interconnecting said tube and pressure fluid source for adjusting the quantity of pressure fluid in said tube and correspondingly the distance between said cover and casing to vary the position of said anodes with respect to said casing.

2. Apparatus according to claim 1 wherein said casing is provided with an edge portion along said opening and said cover is provided with a corresponding coacting edge portion, and said tube is interposed operatively between said casing and cover along said edge portions to define a seal thereat which is capable of adjusting the distance between said cover and casing and of varying the position of said anodes with respect to said casing in dependence upon the quantity of pressure fluid in said tube.

3. Apparatus according to claim 2 wherein said tube is subdivided into a plurality of separate chambers each correspondingly in flow communication with said pressure fluid source.

4. Apparatus according to claim 2 wherein said pressure fluid source includes a pump, valve means and a pressure fluid-containing flow circuit operatively interconnecting said pump and valve means with said tube.

5. Apparatus according to claim 4 wherein said valve means include an inlet valve for flow of pressure fluid to said tube and an outlet valve for flow of pressure fluid from said tube, said inlet valve having a larger operative flow cross-section than said outlet valve.

6. Apparatus according to claim 4 wherein said casing contains a cathode normally electrochemically interconnecting with said anodes to form an electrochemical cell and said control means includes a voltmeter operatively connected externally of the cell between said anodes and said cathode to measure the cell voltage, and regulating pulse transmitter and pulse converter means operatively interconnected with said voltmeter and said valve means to sense changes in cell voltage and control in turn the valve means and flow therethrough to and from said tube in dependence upon said changes.

7. Apparatus according to claim 1 wherein said electrochemical cell is an electrolysis cell for electrolysis of alkali metal chloride, said casing includes means defining an opening at its upper end having a substantially upwardly facing edge portion and said cover includes a correspondingly coacting substantially downwardly facing edge portion for registry with such casing edge portion, said tube is disposed on said casing edge portion and nor mally liftably carries said cover thereon at such cover edge portion to seal such casing opening via said tube substantially only by the weight of said cover, said anodes extend through said cover in fixed position condition with respect thereto to provide correspondingly an upper exterior anode portion and a downward interior anode portion, the exterior anode portions of said anodes having corresponding flexible connectors for connection with a common exterior conductor rail and the interior anode portions of said anodes extending into said casing, and said casing contains a cathode to form the electrolysis cell with said interior anode portions of said anodes.

8. Method of adjusting the position of a group of anodes with respect to the cathode of an electrochemical cell including a casing containing such cathode and having an opening at the upper end thereof normally closed by a cover in which such anodes are mounted, which comprises maintaining pressure fluid in a confined tubular zone, of transverse height which varies in dependence upon the quantity of pressure fluid in said zone, while said zone is operatively between and in sealing contact with said casing and cover and normally carries the weight of said cover, sensing the cell voltage between the anodes and cathode, and adjusting the quantity of pressure fluid in said zone in dependence upon changes in the sensed cell voltage to adjust correspondingly the transverse height of said zone and in turn the position of said cover and said group of anodes with respect to the cathode.

9. Method according to claim 8 wherein the sensed voltage is converted into a regulating pulse and in turn into a control pulse, and wherein said control pulse operates valve means which adjust the quantity of pressure fluid in said zone in dependence upon changes in the sensed cell voltage.

References Cited UNITED STATES PATENTS 2,517,528 8/1950 Moore 204225X 2,542,989 2/1951 Carter et a1. 204-225 3,390,070 6/ 1968 Cooper et a1 204225 3,396,095 8/1968 Diest et al. 204--225 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner US. Cl. X.R. 2()4250, 286 

